1. Field of the Invention
The present invention relates generally to a noise eliminating circuit for video television signals, and is directed more particularly to a noise eliminating circuit for video television signals which is particularly suited for use with a magnetic recording and/or reproducing apparatus, such as, a video tape recorder.
2. Description of the Prior Art
In general, when a monochrome or color video television signal recorded on a magnetic tape or sheet is reproduced by a reproducing magnetic head, the resulting reproduced signal is transmitted to an output terminal through a reproducing circuit which includes components, such as a limiter, an FM-demodulator and so on, which have non-linear characteristics, so that the reproduced video signal is distorted, and especially its high frequency band components are emphasized unnecessarily. More particularly, as a result of high frequency band compensation, an overshoot noise directed to the black level side is produced at the front porch of the horizontal blanking period, and this overshoot noise and the horizontal synchronous pulse can not be distinguished from each other in the video signal reproducing circuit loop, with the result that a disturbance in synchronization may occur.
In general, in the above described reproducing circuit for a video signal, there is usually provided a de-emphasis circuit. Since this de-emphasis circuit corresponds, in circuit operation, to a pre-emphasis circuit which is provided in the recording circuit and serves to prevent high frequency band components of the video signal from being affected by noises in the recording circuit during the recording operation, the de-emphasis circuit cannot compensate for the overshoot noise produced by the components with non-linear characteristics and a disturbance in synchronization may occur.